Growth and evolution of residual stress of AlN films on silicon (100) wafer

Aluminium nitride (AlN) thin films are being extensively used for diverse applications. However, its use significantly depends on the minimization residual stress generated during the deposition process. This paper reports the evolution of residual stress in sputter deposited AlN thin films on Si (100) substrates with varying thickness. The deposited films were found to be polycrystalline wurtzite structure with orientations along (100) for low value of thickness (300 nm and 430 nm) and (002) preferred oriented for thicker films (630 nm and 830 nm). Residual stresses in the AlN films were estimated by x-ray diffraction, infra-red absorption and wafer curvature techniques. Determined Residual stresses were found to be matching well with each other and were compressive in nature. Residual stresses in the AlN thin films were found to decrease (from −2.1 GPa to −0.6 GPa) with the increase in film thicknesses.